Knee prosthesis



FIG. 1 is a right side elevation view of the knee prosthesis showing my new design, the left side elevation view being a mirror image thereof;

FIG. 2 is a rear elevation view thereof;

FIG. 3 is a front elevation view thereof;

FIG. 4 is a bottom plan view thereof;

FIG. 5 is a top plan view thereof; and,

FIG. 6 is a rear and left side perspective view thereof. 

The ornamental design for a knee prosthesis, as shown and described. 